Siding Layers Cause Problems Down the Track

One of my readers sent me a question that I thought I would share this week. She said, “Dear Bob, we are thinking about getting our house re-sided but we are unsure if we should have our old wood shakes removed or if it’s better to just put new vinyl siding over the top of the old material. What would you suggest?”

I love this question because it addresses an issue that I see all the time on the job. If you’re having new siding installed and you’re on a budget, your contractor may suggest just leaving the old material on the home so they don’t have to charge you for the extra time and labor it takes to rip it off. While this is absolutely an option, there are a few reasons why it’s better to have the shakes removed and start fresh.

Firstly, the only way to check for water or termite damage is to get behind the original wood or siding material. If you’ve had issues with leaks in the past, this will only get worse if the new siding is laid over existing, rotting material.

Another point is that installing vinyl siding on top of another material such as wood shakes is difficult because it’s not a flat surface. This makes it more likely that the new siding will warp or show bumps, and it becomes increasingly probable that water will get underneath. If you’re thinking that an issue like that would be covered by the product's warranty, you’re wrong. Most siding manufacturers will void a warranty on a product that’s laid over an existing layer because it hasn’t been installed the way it was intended to be.

Something else to think about is that when you layer siding, it ends up sticking out further than your windows, which can obstruct the view outside and will leave the windows very susceptible to leak problems. I’ve seen this same issue on homes with shallow roof eaves. When there isn’t enough room for the water to run away from the house, it runs down the siding and eventually into it.

Finally, ripping away the old material and putting on new gives you the opportunity to put more insulation in your home, which keeps it warmer in the winter and cooler in the summer. A full wrap also protects your home from potential damage and ensures that the warranty will stick if anything was to happen.

So, in a nutshell, I completely understand why a homeowner would want to put new siding on top of their existing material and I agree that the option will offer cost savings in the short term. The question I would ask is if it’s worth the risk of potential problems that can arise during the lifetime of the newly installed product. My advice is to make sure to weigh all your options and ask plenty of questions before you make your decision. Good luck!

Bob O’Donnell is the owner of O’Donnell Bros. Inc., a Bristol-based home improvement company established in 1975. Email your questions for Bob to info@odonnellbros.com with the subject line “Ask the Pro.” All questions may be considered for publication. To contact Bob for your remodeling needs, call O’Donnell Bros. Inc. at (860) 589-5155 or visit http://www.odonnellbros.com. Advice is for guidance only. Get in touch.